Display updates of some
smtpd(8) internal counters in
one second intervals. Each line reports the increment of all counters
since the last update, except for some counters which are always absolute
values. The first line reports the current value of each counter. The
fields are:

Display the list of known remote MX hosts. For each of
them, it shows the IP address, the canonical hostname, a reference count,
the number of active connections to this host, and the elapsed time since
the last connection.

Display the list of currently active relays and associated
connectors. For each relay, it shows a number of counters and information
on its internal state on a single line. Then comes the list of connectors
(source addresses to connect from for this relay).

Display status of routes currently known by
smtpd(8). Each line consists
of a route number, a source address, a destination address, a set of
flags, the number of connections on this route, the current penalty level
which determines the amount of time the route is disabled if an error
occurs, and the delay before it gets reactivated. The following flags are
defined:

D

The route is currently disabled.

N

The route is new. No SMTP session has been established
yet.

Q

The route has a timeout registered to lower its penalty
level and possibly reactivate or discard it.

Updates the contents of table
name, for tables using the
“file” backend.

When smtpd receives a message, it generates a
message-id for the message, and one
envelope-id per recipient. The
message-id is a 32-bit random identifier that
is guaranteed to be unique on the host system. The
envelope-id is a 64-bit unique identifier
that encodes the message-id in the 32 upper
bits and a random envelope identifier in the 32 lower bits.

A command which specifies a message-id applies
to all recipients of a message; a command which specifies an
envelope-id applies to a specific recipient
of a message.